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171.
Microbial Community Structure and Dynamics of Dark Fire-Cured Tobacco Fermentation 总被引:2,自引:0,他引:2 下载免费PDF全文
Michele Di Giacomo Marianna Paolino Daniele Silvestro Giovanni Vigliotta Francesco Imperi Paolo Visca Pietro Alifano Dino Parente 《Applied microbiology》2007,73(3):825-837
The Italian Toscano cigar production includes a fermentation step that starts when dark fire-cured tobacco leaves are moistened and mixed with ca. 20% prefermented tobacco to form a 500-kg bulk. The dynamics of the process, lasting ca. 18 days, has never been investigated in detail, and limited information is available on microbiota involved. Here we show that Toscano fermentation is invariably associated with the following: (i) an increase in temperature, pH, and total microbial population; (ii) a decrease in reducing sugars, citric and malic acids, and nitrate content; and (iii) an increase in oxalic acid, nitrite, and tobacco-specific nitrosamine content. The microbial community structure and dynamics were investigated by culture-based and culture-independent approaches, including denaturing gradient gel electrophoresis and single-strand conformational polymorphism. Results demonstrate that fermentation is assisted by a complex microbial community, changing in structure and composition during the process. During the early phase, the moderately acidic and mesophilic environment supports the rapid growth of a yeast population predominated by Debaryomyces hansenii. At this stage, Staphylococcaceae (Jeotgalicoccus and Staphylococcus) and Lactobacillales (Aerococcus, Lactobacillus, and Weissella) are the most commonly detected bacteria. When temperature and pH increase, endospore-forming low-G+C content gram-positive bacilli (Bacillus spp.) become evident. This leads to a further pH increase and promotes growth of moderately halotolerant and alkaliphilic Actinomycetales (Corynebacterium and Yania) during the late phase. To postulate a functional role for individual microbial species assisting the fermentation process, a preliminary physiological and biochemical characterization of representative isolates was performed. 相似文献
172.
Minerals such as titanium dioxide, TiO2, and zinc oxide, ZnO, are well known active semiconductor photocatalysts used extensively in heterogeneous photocatalysis to destroy environmental pollutants that are organic in nature. They are also extensively used in sunscreen lotions as active broadband sunscreens that screen both UVB (290-320 nm) and UVA (320-400 nm) sunlight radiation and as high SPF makers. When so photoactivated by UV light, however, these two particular metal oxides are known to generate highly oxidizing radicals (OH and ) and other reactive oxygen species (ROS) such as H2O2 and singlet oxygen, 1O2, which are known to be cytotoxic and/or genotoxic. Hydroxyl (OH) radicals photogenerated from photoactive TiO2 specimens extracted from commercial sunscreen lotions [R. Dunford, A. Salinaro, L. Cai, N. Serpone, S. Horikoshi, H. Hidaka, J. Knowland, FEBS Lett. 418 (1997) 87] induce damage to DNA plasmids in vitro and to whole human skin cells in cultures. Accordingly, the titanium dioxide particle surface was modified to produce TiO2 specimens of considerably reduced photoactivity. Deactivation of TiO2 diminishes considerably, in some cases completely suppresses damage caused to DNA plasmids, to human cells, and to yeast cells compared to non-modified specimens exposed to UVB/UVA simulated solar radiation. The photostabilities of sunscreen organic active agents in neat polar and apolar solvents and in actual commercial formulations have been examined [N. Serpone, A. Salinaro, A.V. Emeline, S. Horikoshi, H. Hidaka, J. Zhao, Photochem. Photobiol. Sci. 1 (2002) 970]. With rare exceptions, the active ingredients undergo photochemical changes (in some cases form free radicals) and the sunscreen lotions lose considerable Sun protection efficacy only after a relatively short time when exposed to simulated sunlight UVB/UVA radiation, confirming the recent findings by Sayre et al. [R.M. Sayre, J.C. Dowdy, A.J. Gerwig, W.J. Shields, R.V. Lloyd, Photochem. Photobiol. 81 (2005) 452]. 相似文献
173.
Di Fabio R Alvaro G Bertani B Donati D Pizzi DM Gentile G Pentassuglia G Giacobbe S Spada S Ratti E Corsi M Quartaroli M Barnaby RJ Vitulli G 《Bioorganic & medicinal chemistry letters》2007,17(5):1176-1180
Chiral tetrahydroquinoline derivatives have been prepared by an asymmetric Mannich-type condensation reaction using commercially available vinyloxyethylsilane and a N-arylimino R-(+)-t-butyl lactate ester, in the presence of a catalytic amount of metal triflates as Lewis acids. This synthetic approach gave rise to the target aldehyde intermediate in moderate facial diastereoselectivity and in high chemical yield. This efficient route enabled to scale up the synthesis of an orally bioavailable glycine antagonist showing outstanding in vivo anti-hyperalgesic activity in different animal models of sustained inflammation and chronic neuropathic pain. 相似文献
174.
During the G1/S transition, p21 proteolysis is mediated by Skp2; however, p21 reaccumulates in G2 and is degraded again in prometaphase. How p21 degradation is controlled in mitosis remains unexplored. We found that Cdc20 (an activator of the ubiquitin ligase APC/C) binds p21 in cultured cells and identified a D box motif in p21 necessary for APC/C(Cdc20)-mediated ubiquitylation of p21. Overexpression of Cdc20 or Skp2 destabilized wild-type p21; however, only Skp2, but not Cdc20, was able to destabilize a p21(D box) mutant. Silencing of Cdc20 induced an accumulation of p21, increased the fraction of p21 bound to Cdk1, and inhibited Cdk1 activity in p21(+/+) prometaphase cells, but not in p21(-/-) cells. Thus, in prometaphase Cdc20 positively regulates Cdk1 by mediating the degradation of p21. We propose that the APC/C(Cdc20)-mediated degradation of p21 contributes to the full activation of Cdk1 necessary for mitotic events and prevents mitotic slippage during spindle checkpoint activation. 相似文献
175.
MicroRNA-133 controls cardiac hypertrophy 总被引:23,自引:0,他引:23
176.
David Gazzieri Marcello Trevisani Jochen Springer Selena Harrison Graeme S. Cottrell Eunice Andre Paola Nicoletti Daniela Massi Sandra Zecchi Daniele Nosi Marco Santucci Norma P. Gerard Monica Lucattelli Giuseppe Lungarella Axel Fischer Eileen F. Grady Nigel W. Bunnett Pierangelo Geppetti 《Free radical biology & medicine》2007,43(12):1670
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Andrew G. Stephen Siddhartha A.K. Datta Karen M. Worthy Lakshman Bindu Matthew J. Fivash Kevin B. Turner Daniele Fabris Alan Rein Robert J. Fisher 《Journal of biomolecular techniques》2007,18(4):259-266
The interaction of the HIV Gag polyprotein with nucleic acid is a critical step in the assembly of viral particles. The Gag polyprotein is composed of the matrix (MA), capsid (CA), and nucleocapsid (NC) domains. The NC domain is required for nucleic acid interactions, and the CA domain is required for Gag-Gag interactions. Previously, we have investigated the binding of the NC protein to d(TG)(n) oligonucleotides using surface plasmon resonance (SPR) spectroscopy. We found a single NC protein is able to bind to more than one immobilized oligonucleotide, provided that the oligonucleotides are close enough together. As NC is believed to be the nucleic acid binding domain of Gag, we might expect Gag to show the same complex behavior. We wished to analyze the stoichiometry of Gag binding to oligonucleotides without this complication due to tertiary complex formation. We have therefore analyzed Gag binding to extremely low oligonucleotide density on SPR chips. Such low densities of oligonucleotides are difficult to accurately quantitate. We have determined by Fourier transform ion cyclotron (FTICR) mass spectrometry that four molecules of NC bind to d(TG)(10) (a 20-base oligonucleotide). We developed a method of calibrating low-density surfaces using NC calibration injections. Knowing the maximal response and the stoichiometry of binding, we can precisely determine the amount of oligonucleotide immobilized at these very-low-density surfaces (<1 Response Unit). Using this approach, we have measured the binding of Gag to d(TG)(10). Gag binds to a 20-mer with a stoichiometry of greater than 4. This suggests that once Gag is bound to the immobilized oligonucleotide, additional Gag molecules can bind to this complex. 相似文献